1. Field of the Invention
The present invention relates to a Venetian blind, more particularly to a Venetian blind with a plurality of upper slats whose tilting angle can be adjusted independently from the tilting angle of a plurality of lower slats.
2. Description of the Related Art
A conventional Venetian blind includes a hollow horizontal headrail, a horizontal rotary shaft journalled in the headrail, a plurality of slats suspended one above another from the headrail, a bottom rail disposed below the slats, an operating rod for controlling tilting of the slats, two pairs of ladder cords, and a pair of pull ropes. Each of the ladder cords is disposed at a longitudinal side of a respective end portion of each of the slats, and has a top end secured to the rotary shaft and a bottom end secured to the bottom rail such that axial rotation of the rotary shaft can cause the ladder cords to move up and down in order to tilt the slats. The operating rod is coupled to the rotary shaft, and is operable to actuate axial rotation of the rotary shaft, thereby controlling tilting of the slats. Each of the pull ropes passes through an aperture formed in a respective end portion of each of the slats, and has one end secured to the bottom rail, and another end extending out of the housing.
The aforementioned Venetian blind achieves the purposes of raising and lowering the slats and adjusting the tilting angle of the slats to control passage of light through the Venetian blind. However, all of the slats are adjusted simultaneously with respect to their tilting angles by operating the operating rod. When the slats are adjusted at a desired tilt to permit passage of an amount of light through the Venetian blind and into an interior, the interior might be visible from the outside through clearances among the slats. In the conventional Venetian blind, it is not possible to adjust the slats to permit passage of light through the Venetian blind while blocking vision into the interior for ensuring privacy at the same time.
Therefore, the main object of the present invention is to provide a Venetian blind with slats that can be adjusted in a manner to permit passage of light therethrough while ensuring user privacy.
Accordingly, the Venetian blind of the present invention includes a hollow horizontal headrail, upper and lower slat units, a bottom rail, two pull ropes, and first and second angle-adjusting mechanisms. The upper slat unit includes a plurality of parallel upper slats disposed under and parallel to the headrail. Each of the upper slats has two end portions that are opposite to each other along a longitudinal direction of a respective one of the upper slats. Each of the end portions is formed with a hole therethrough. The lower slat unit includes a plurality of parallel lower slats disposed under and parallel to the upper slats. Each of the lower slats has two end portions that are opposite to each other along a longitudinal direction of a respective one of the lower slats. Each of the end portions of the lower slats is formed with a hole therethrough. The bottom rail is disposed under and parallel to the lower slats, and has two end portions that are opposite to each other with respect to a longitudinal direction of the bottom rail. The pull ropes extend respectively through the holes in each of the upper and lower slats, and pass through the headrail. Each of the pull ropes has a mounting end that is fastened to a respective one of the end portions of the bottom rail, and an actuator end that is opposite to the mounting end and that is suspended from the headrail. The actuator end is actuatable to adjust raising and lowering of the upper and lower slats. The first angle-adjusting mechanism includes a first rotating shaft journalled within the headrail and extending along a longitudinal direction of the headrail, a first adjustment rod connected operatively to the first rotating shaft and capable of being actuated to rotate the first rotating shaft, and two first positioning cord units mounted respectively on two end portions of the first rotating shaft and connected respectively to the end portions of each of the upper slats. Each of the first positioning cord units includes two first ladder cords that have upper ends secured to the first rotating shaft and that abut respectively against two opposite longitudinal sides of each of the upper slats, and a plurality of parallel first slat-supporting cords, each of which is disposed under a respective one of the upper slats and has two opposite ends that are disposed respectively at the longitudinal sides of each of the upper slats and that are fastened respectively to the first ladder cords. The second angle-adjusting mechanism includes a second rotating shaft journalled within the headrail and extending along the longitudinal direction of the headrail, a second adjustment rod connected operatively to the second rotating shaft and capable of being actuated to rotate the second rotating shaft, and two second positioning cord units mounted respectively on two end portions of the second rotating shaft and connected respectively to the end portions of each of the lower slats. Each of the second positioning cord units includes two second ladder cords that have upper ends secured to the second rotating shaft and that abut respectively against two opposite longitudinal sides of each of the lower slats, and a plurality of parallel second slat-supporting cords, each of which is disposed under a respective one of the lower slats and has two opposite ends that are disposed respectively at the longitudinal sides of each of the lower slats and that are fastened to the second ladder cords. The tilting angle of the upper slats can be adjusted independently from that of the lower slats.